The percent composition calculator is a handy tool in chemistry that determines the relative abundance of each element in a compound.
It expresses this as a percentage of the compound’s total mass. This calculator simplifies complex calculations, providing quick and accurate results for various chemical analyses.
For instance, consider water (H₂O). A percent composition calculator would reveal that it consists of approximately 11.19% hydrogen and 88.81% oxygen by mass.
Percent Composition Calculator
| Compound | Element | Mass (g) | Total Mass (g) | Percent Composition |
|---|---|---|---|---|
| H₂O | H | 2.02 | 18.02 | 11.19% |
| H₂O | O | 16.00 | 18.02 | 88.81% |
| CO₂ | C | 12.01 | 44.01 | 27.29% |
| CO₂ | O | 32.00 | 44.01 | 72.71% |
| NH₃ | N | 14.01 | 17.04 | 82.22% |
| NH₃ | H | 3.03 | 17.04 | 17.78% |
Percent Composition Formula
For any element in a compound, it’s expressed as:
% Composition = (Mass of element / Total mass of compound) × 100Let’s apply this to calcium carbonate (CaCO₃):
Calculate the molar mass: Ca (40.08 g/mol) + C (12.01 g/mol) + 3 × O (15.99 g/mol) = 100.07 g/mol
For calcium: % Ca = (40.08 g / 100.07 g) × 100 = 40.05%
For carbon: % C = (12.01 g / 100.07 g) × 100 = 12.00%
For oxygen: % O = (3 × 15.99 g / 100.07 g) × 100 = 47.95%
How do you find the composition of a percentage?
To determine the percentage composition:
- Identify the compound’s chemical formula.
- Calculate the molar mass of the compound.
- Determine the mass of each element.
- Apply the percent composition formula for each element.
Find the percentage composition of sulfuric acid (H₂SO₄)
Molar mass: 2(1.01) + 32.07 + 4(16.00) = 98.09 g/mol
Mass of H: 2.02 g
Mass of S: 32.07 g
Mass of O: 64.00 g
% H = (2.02 / 98.09) × 100 = 2.06%
% S = (32.07 / 98.09) × 100 = 32.69%
% O = (64.00 / 98.09) × 100 = 65.25%
What is the percent composition of H in C₁₀H₂₀?
To calculate the percent composition of hydrogen in C₁₀H₂₀:
- Molar mass of C₁₀H₂₀: 10(12.01) + 20(1.01) = 140.30 g/mol
- Mass of H: 20 × 1.01 = 20.20 g
- % H = (20.20 / 140.30) × 100 = 14.40%
Thus, hydrogen constitutes 14.40% of C₁₀H₂₀ by mass.
What is the percentage composition of Na?
For sodium (Na), being an element rather than a compound, the percent composition is always 100%.
Molar mass of NaCl: 22.99 + 35.45 = 58.44 g/mol
% Na = (22.99 / 58.44) × 100 = 39.34%
Sodium comprises 39.34% of the mass in table salt (NaCl).
How do you find grams from percent composition?
To determine the mass of an element from percent composition.
We know S is 32.69% of H₂SO₄.
32.69% = 0.3269
Grams of S = 0.3269 × 250 g = 81.73 g
81.73 g of sulfur are present in 250 g of sulfuric acid.
Sources / Reference URLs
- American Chemical Society – Percent Composition
- Khan Academy – Mass percent composition
- National Institute of Standards and Technology – Atomic Weights and Isotopic Compositions
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